Metallic components include both amalgam materials and casting alloys. Amalgams are used primarily as filling materials while casting alloys are used in crowns and bridges, as bases for ceramic restorations, and in orthodontic work.
The first, and perhaps most talked about types of dental restoration materials, are amalgam fillings. An amalgam is obtained by mixing mercury with other metals; this mixture can then be used to fill a cavity. The mixture is often liquid or very near to a liquid at room temperature, so it can easily form to the contours of a cavity and fill the space very effectively. Recently, an increasing number of patients are moving away from amalgam fillings for a variety of reasons – some for aesthetic reasons, others because of concerns about the mercury content or concerns over metallic components in general.
Many other dental restorations use gold or other precious metal-based casting alloys, and are most commonly used in crowns. While pure gold is much too soft to make effective dental restorations, it has many other properties that make it an ideal starting material for dental alloys. Several other metals are commonly mixed with gold in order to obtain an alloy that combines the most favorable properties of each metal. Gold and platinum are often selected because they are resistant to tarnish and corrosion and often demonstrate only very minimal immune reactivity in the Biocompatibility testing. Metals like copper and palladium are used to modify the color of the alloy, while others such as silver and iridium are used to give the alloy more strength. There are even more metals that are used in dental work to alter melting points, hardness, color, and the durability of alloys. Any given alloy could have up to a dozen different component metals, so it is important to know which metals you will substantially react to before they are placed in the mouth.